1. Technical Field of the Invention
The present invention generally relates to wastewater processing. More particularly, the present invention is directed to a wastewater processing apparatus and a wastewater processing method for the processing of animal manure wastewater.
2. Description of the Prior Art
It is known to process raw animal manure wastewater for mechanical separation and thickening in order to produce, on the one hand, a sludge of high consistency and content of residuals, such as nutrients (e.g., phosphorous and nitrogen compounds), and on the other hand, a liquid (i.e., filtrate) with low content of residuals that can be easily disposed, e.g., by spraying on agricultural fields.
EP 498 337 discloses a state of the art process that uses a centrifuge. This process requires high energy input and produces a comparatively low consistency of sludge (i.e., with still considerable fluid content). Furthermore, due to the high energy input, the residuals tend to disintegrate, resulting in a high degree of resolved nutrients (especially phosphorous and nitrogen) in the filtrate.
A screw press is known for compressing sludge. The screw press requires an inlet consistency of sludge having low water content. Furthermore, the screw press is sensitive to fluctuations in feed conditions and composition of the sludge.
EP 254 841 discloses a device for processing of manure comprising a drum filter unit.